Add test for HEAD queries on Swift tempurl MW

Last version of Swift tempurl MW allow HEAD request
even if PUT or GET are not allowed. This patch
tests that feature.
Related Swift commit: d18b6d8d5d6ca8c0adf3b98b488042c49394a072

This patch also provides some code refactoring to the
middleware.

Change-Id: I33a3f73cf61a0c044428f885154feccb93c672ac
Merge "Add test for HEAD queries on Swift tempurl MW"